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Duke Energy apologizes to customers, says electricity demand led to blackouts on Christmas Eve

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Duke Energy apologized to customers on Tuesday and explained what caused ongoing blackouts that left half a million people without power over Christmas weekend.

Duke Energy leaders reported the findings of their investigation to the North Carolina Utilities Commission at 10 am Tuesday, saying they are “incredibly sorry” to all those affected by the blackouts.

“We recognize what happened,” said Julie Jansen, CEO of Duke Energy Carolina. “We’ve set out a path to ensure that if we face similar challenges, we’ll see a different outcome.”

Leaders said a combination of factors led Duke Energy to use continuous blackouts for the first time in the utility’s history, adding that the program designed to manage blackouts did not work properly. According to Duke, the rapid drop in temperatures in late December 23rd and early December 24th caused an increase in demand for electricity, which exceeded projections and reduced generating capacity. Duke Energy said it was forced to initiate automatic power outages as a result of demand.

“We recognize that the outages themselves lasted much longer than we expected,” said Jansen.

Duke North Carolina President Kendal Bowman said power demand was about 10% higher than expected because outside temperatures dropped faster than anticipated. At the same time, she said, the company suddenly lost about half of power generation at three plants because instrumentation froze in the cold, despite the utility’s weather protection.

“The temperatures were not only much lower than typical for our region, they also dropped at a very rapid rate,” Bowman said. “It got a lot colder, a lot faster than what we normally see here in the Carolinas.”

Duke Energy spokesman Jeff Brooks echoed Bowman’s sentiments on the weather conditions.

“The conditions we were dealing with were the same conditions that were being dealt with across the Southeast and much of the East Coast,” Brooks said. “And so, it created a situation where it was very difficult to get assistance, even things that we had already booked and scheduled in our system.”

When they turned to the grid to buy additional power, it was not available.

“The resources we were counting on to meet the predicted energy load were also affected by weather conditions,” Bowman said. “Between midnight and early Saturday morning, we lost about 1,300 megawatts of power generation capacity due to equipment malfunctions… and the power we purchased from out of state did not materialize.”

Duke had never used continuous blackouts before, and the automated program that was supposed to manage them didn’t work. Operators had to manually perform shutdowns and restarts, which took longer than expected.

“These measures that were taken were absolutely necessary and were an important step in maintaining network reliability and avoiding a potentially longer or greater outage,” said Brooks.

Duke said energy projections were far below demand. Unable to obtain power from neighboring states, the utility ran out of reserves. For the first time in the company’s history, Duke has instituted continuous outages – known as load shedding.

Using an automated tool, Duke removed 234 circuits and restored power, but the program stopped working.

“The automated tool did not respond to these load shedding commands, requiring operators to begin performing the necessary activities to manually manage the load,” said Scott Batson, senior vice president and director of distribution for Duke Energy.

Outages that were supposed to last 15-30 minutes instead lasted for hours.

Executives said the program was tested in early December and they are investigating what caused the tool to fail.

Duke executives said the alternative to the blackouts would be to disrupt the statewide power grid. They said if they were in the same situation again they would have to do the same thing but said they will learn from mistakes to try to avoid this in the future.

“This is the first time in our company’s history that we have had to implement continuous service outages, and while most of our plants performed well during the storm, the outage process did not go as smoothly as we would have liked,” said Bowman. . .

“It’s a computerized system. It’s automated,” he said. “The system detects where there’s a challenge and turns off the power there. So it’s really automated. We can’t say, ‘Yes, keep this neighborhood online, but not that one.’ It doesn’t work like that. It’s an automated process.”

Governor Roy Cooper’s press secretary, Sam Chan, provided WRAL News with information on how cold weather compromised five Duke Energy facilities. It included the following facilities:

  • Dan River, Roxboro and Mayo having units reduced overnight from December 23rd to 24th.
  • Duke Energy also told the North Carolina Utilities Commission that a Lincoln CT went offline.
  • Duke Energy also said that Smith derailed on the morning of December 24.

“It appears that the extra plants were two plants that experienced some reduction in cold weather generation, but AFTER peak demand hours,” Brooks wrote in an email to WRAL News. “So they were not a factor in the event and we were able to safely meet customers’ electricity demand on Christmas Day when these units returned to full service.

“One was a DEP facility, Smith Energy Complex in Richmond County. The other was a DEC facility, Buck Combined Cycle Plant, in Rowan County.”

While the widespread extreme cold was predicted well in advance, Duke acknowledges he was taken by surprise. Some generators failed and power was not available in nearby states with similar weather.

The energy company has been investigating aging infrastructure as a cause of the blackouts. Duke Energy said the current investments it had already made in infrastructure prevented the problems from getting worse.